Wow, very cool story, thanks ! Even I would have bought that Galaga without blinking my eye..... 
Does that manual have any drawings or pictures from the inside of the cab, i mean the PSU, how the wiring ran etc. (At least something I will understand
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That would be a great help for my restoration. I hope to bring everything back in original condition, well as much as possible.....
I'll take a look again, I'm not sure how useful manual would be since it's for the cocktail and I recall it being pretty sparse. For sure it's just drawings, no pics.
One interesting thing about the Galaga (and I'm not sure if Galaxian was the same) cabinet is that there's a built-in edge connector junction where the main cabinet harness goes, much like in a Sega Aero City cabinet. IIRC, this is mounted to a plate on the wall under the PCB, so in theory you could make an adapter to whichever PCB to go to the main cabinet harness.
Actually, not unlike what is seen here (except the PCB side would have an edge connector):
